1. Field of the Invention
The present invention relates to a paper feeding apparatus. Particularly, although not exclusively, the apparatus is designed to automatically and accurately feed papers one by one at generally regular intervals into a paper receiving apparatus, for example, a facsimile machine or a photocopier.
2. Description of the Background Art
In a conventional facsimile machine, sheets of paper are fed in consecutive order, from a paper feeding tray into the machine which then scans each sheet in turn to generate a transmission signal which is transmitted to a location identified by a user.
A known device for feeding the papers into a facsimile machine is illustrated in FIG. 1 of the accompanying drawings which is a front view of part of a paper feeding apparatus, and FIG. 2 which is a perspective view showing essential parts of the apparatus of FIG. 1 separated.
In the Figures a paper feeding roller 1, for separately feeding respective sheets of paper loaded on a paper feeding tray (not shown) is supported by a frame 3. A spring clutch 5, supported in part by a bushing 4, is provided to connect or cut torque which is delivered from an outside power source, for example, a motor (not shown). A paper feeding gear 6 delivers the torque to an axle 2 of the paper feeding roller 1.
The spring clutch 5 is engaged with the cylindrical part of paper feeding gear 6 and the cylindrical part of bushing 4 in a rotatable direction. A transfer roller 7 which is positioned parallel to the paper feeding roller 1 to transfer the respective papers is also supported by the frame 3. A pinch roller 12, arranged to co-operate with the transfer roller 7, is supported in another frame (not shown). A transfer gear 8 is fixed to an end of the transfer roller 7 and receives torque delivered from the outside, and in turn delivers the torque to the transfer roller 7. When the respective papers 9 are fed to the paper feeding roller 1 from the paper feeding tray, the paper feeding gear 6, having received power from the outside, drives the paper feeding roller 1 in the direction indicated by arrow "A" via the spring clutch 5 and the bushing 4.
As the transfer roller 7 turns faster than the paper feeding roller 1, when the paper 9 is fed from the paper feeding tray by the rotation of the transfer roller 7, the paper is under tension due to the difference in speed between the two rollers 1 and 7. Thus, a phase progress difference .DELTA..THETA. between the bushing 4, the transfer roller 7 and the paper feeding gear 6 occurs. As an outer end 5b of the spring clutch 5 is inserted into a notch part 6b of the paper feeding gear sleeve 6a, and at the same time, an inner end of the spring clutch 5a is laid across the notch part 4a of the bushing 4, rotation of the bushing 4 in the direction indicated by arrow "A" enables the spring clutch 5 to loosen, and some degree of the torque is absorbed and accumulated in the spring clutch 5. The phase progress difference progresses properly according to the length of the paper by means of composition of the outer end 5b of the spring clutch inserted into the notch part 6b of paper feeding gear 6 for the paper feeding roller 1. The phase progress difference .DELTA..THETA. remains until the rear end of the paper leaves the paper feeding roller 1 and a succeeding paper is fed onto the paper feeding roller 1.
Consequently, the conventional paper feeding device torque is accumulated in the spring clutch 5, since the spring clutch 5, which controls the revolution of the paper feeding roller 1, is loosened to the extent of the phase progress difference .DELTA..THETA., due to a difference in speed of revolution between the bushing 4 provided over the axle 2 of the paper feeding roller 1, and the paper feeding gear 6. The accumulated torque debars the paper feeding roller 1 from rotating at the same speed as the speed of the transfer roller 7. The longer the sheet of paper 9, the more serious the debarment. Therefore, there is a problem with the conventional paper feeding device in that it is difficult to maintain an interval between the papers that permits a sensor which senses a succeeding paper because if the interval between the papers is too narrow.